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Revised by Approved
Manoeuvring Committee of 23rd ITTC 23rd ITTC 2002
Date Date 2002
CONTENTS
1 PURPOSE OF PROCEDURE
2 RECOMMENDED PROCEDURES
FOR MANOEUVRING TRIALS
2.1 Trial Conditions
2.1.1 Environmental Restrictions
2.1.2 Loading Conditions
2.1.3 Approach Conditions
2.2 Test procedures and parameters
to be obtained
2.2.1 Turning Circle
2.2.2 Zigzag Manoeuvre (Z-
Manoeuvre)
2.2.3 Modified Zigzag Manoeuvre2.2.4 Zigzag Manoeuvre at Low Speed
2.2.5 Spiral Manoeuvre
2.2.6 Pullout Test
2.2.7 Stopping Test
2.2.8 Stopping Inertia Test
2.2.9 Man-overboard Test
2.2.10 Parallel Course Manoeuvre Test
2.2.11 Initial Turning Test
2.2.12 Accelerating Turning Test
2.2.13 Thruster Test
2.2.14 Crabbing Test
3 PARAMETERS
3.1 Ship Parameters3.2 Manoeuvring Trial Measurements3.2.1 Initial Conditions
3.2.2 Manoeuvring Data
4 DATA ACQUISITION SYSTEM
4.1 Calibration of Instruments4.1.1 Ship speed and position
4.1.2 Ships heading
4.1.3 Rudder angle
4.1.4 Rate of turn
4.1.5 Shaft rpm
4.1.6 Torque
4.2 Acquisition Systems5 VALIDATION
5.1 Uncertainty Analysis5.1.1 Correction due to Environment
5.1.2 Correction due to Ship Conditions
5.2 Benchmark Tests
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Full Scale Manoeuvring Trials Procedure
1 PURPOSE OF PROCEDURE
To provide a guideline for performing full
scale trials to determine ship manoeuvring
characteristics as a reaction to rudder and en-
gine actions.
2 RECOMMENDED PROCEDURES
FOR MANOEUVRING TRIALS
The 23rd ITTC Manoeuvring Committee
has drafted the present procedure based on the
14th ITTC MANOEUVRING TRIAL CODE,
which is supplemented by considering the fol-lowing topics.
For operation purpose, tests must concernfollowing qualities which have been identi-
fied by IMO:
1. inherent dynamic stability,2. course- keeping ability,3. initial turning/course-changing
ability,
4. yaw checking ability,5. turning ability,6. stopping ability.
Table 1 shows a total of 19 manoeuvring
tests recommended by various organisa-
tions. This procedure provides detailed in-
formation on a selection of 15 tests which
provide information on above mentioned
six ship-handling characteristics.
Furthermore, recommendations are formu-lated for operation purposes, including low
speed operation in channels and harbour
environments.
Test procedures should document trials in away which is compatible with both ship de-
sign and scientific purpose (e.g. validation
of predicted manoeuvres).
2.1 Trial Conditions
2.1.1 Environmental RestrictionsManoeuvrability of a ship is strongly af-
fected by interactions with the bottom, banks,passing vessels, wind and waves. Therefore the
trial site should be located in waters of ade-
quate depth with low current and tidal influ-
ence as possible, and manoeuvring trials should
be performed in the calmest possible weather
conditions. It is recommended that
1) the water depth should exceed four timesthe mean draft of the ship;
2) the maximum sea state should be chosentaking into account the ships characteris-tics such as ship speed, ship displacement,
etc. Although IMO Resolution A.751 re-
quires trials not to be conducted with a sea
state greater than 4, some ships may require
sea states as low as 1 in order to provide
accurate full scale data;
3) the maximum wind speed should be chosentaking into account the ships characteris-
tics such as ship speed, ship displacement,
accurate full scale data.
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Table 1: Recommended Manoeuvring Tests by Various Organisations
Type of testIMO
A601
IMO
A751
ITTC
1975
SNAME
1989
Norse
StandardJapan RR ISO
ITTC
2002
Remarks
( * )
1 Turning circle 5
2 Z-manoeuvre test 3,4
3Modified Z-manoeuvre
test- - - - - - 1,3
4Z-manoeuvre at low
speed test 1,2
5 Direct spiral test - - - 1,2
6 Reverse spiral test - - - 1,2
7 Pullout test - - - 1
8 Stopping test 6
9 Stopping inertia test - - - - 6
10 Man-overboard test - - - - - 4,5
11Parallel course manoeu-
vre test - - - - - 4,5
12 Initial turning test - - - - - - 3
13 Accelerating turning test - - - - 5
14 Thruster test - - - 4,5
15 Crabbing test - - - - - - - 3
16 New course keeping test
17Acceleration/deceleration
test
18 Crash stop ahead test
19 Minimum revolution test
(*) 1 inherent dynamic stability
2 course-keeping ability
3 initial turning/course-changing ability
4 yaw checking ability
5 turning ability
6 stopping ability
(22nd ITTC Trials & Monitoring Specialist Committee, 1999)
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Although IMO Resolution A.751 requires trials
not to be conducted with a true wind speed
greater than Beaufort 5, some ships may re-
quire wind speeds not exceeding Beaufort 2 in
order to provide
2.1.2 Loading ConditionsThe Committee recommends that the trials
are to be carried out with the ship in the full-
load condition at zero trim, because in this con-
dition the manoeuvres are most critical, or in a
normal operational condition within a five per-
cent deviation of the full-load draftand trim.
Where it is impractical to conduct trials atfull-load draft, they may be conducted at a
draft as close to full-load draft as possible with
minimum trim, or in a ballast condition with
minimum trim and sufficient propeller immer-
sion.
2.1.3 Approach ConditionsThe approach speed according to IMO is to
be at least 90 per cent of the ships speed corre-
sponding to 85 per cent of the maximum en-
gine output, but some tests should also be car-
ried out at low speed
Before the execution of the relevant ma-
noeuvre, the ship must have run at constant
engine(s) setting with minimum rate of change
of heading (steady course) for at least five min-
utes.
2.2 Test procedures and parameters to be
obtained
2.2.1 Turning CircleTurning circle tests are performed to both
port and starboard at approach speed with a
maximum rudder angle. It is necessary to do a
turning circle of at least 540 degrees to deter-
mine the main parameters of this trial.
Fig. 1 Turning circle: definitions
MAXIMUM
TRANSFER
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The essential information to be obtained
from this manoeuvre consists of (see Figure
1):
tactical diameter, advance, transfer, loss of speed on steady turn, time to change heading 90 degrees time to change heading 180 degreesThe first three of these may be presented in
non-dimensional form by dividing their values
by ship's length between perpendiculars (LPP).
Maximum advance and maximum transfer can
be measured, too.
When it is possible, turning circle at low
speed should be considered.
2.2.2 Zigzag Manoeuvre (Z-Manoeuvre)The zigzag manoeuvre is obtained by re-
versing the rudder alternately by degrees to
either side at a deviation from the initial
course. After a steady approach the rudder is
put over to right (first execute). When theheading is degrees off the initial course, the
rudder is reversed to the same angle to left
(second execute). After counter rudder has
been applied, the ship initially continues yaw-
ing in the original direction with decreasing
yaw rate until it changes sign, so that the ship
eventually yaws to the left in response to the
rudder. When the heading is degrees off the
course left, the rudder is reversed again to right
(third execute). This process continues until a
total of 5 rudder executes have been completed
Figure 2. Time trace of zigzag manoeuvre parameters
(delta - delta dot)
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Hence, a zigzag manoeuvre is determined
by the combination of the values of change of
heading and rudder angle, and is denoted/. Common values for these parameters are
10/10 and 20/20. However, other combinations
can be applied (see 2.2.3).
The manoeuvres are to be executed at ap-
proach speed (see 2.1.3) and if possible at low
speed also.
Zigzag manoeuvres are carried out starting
with both starboard and port rudder, in order to
identify the environmental effects (e.g. wind).
From the nautical point of view, however, i.e.
the interpretation of the international rules of
navigation at sea, the turning and the yaw
checking ability using starboard rudder angles are of special interest, since emergency turns
should be carried out to starboard.
For a first simple analysis of the results,characteristic steering values defined in Fig. 2can be used; the values are plotted as a func-tion of the rudder angle .
Results of zigzag tests are defined as fol-
lows.
Initial turning time ta (s): the time from the
instant the rudder is put at the outset of the
manoeuvre (first execute) until the heading is
degrees off the initial course. At this instant
the rudder is reversed to the opposite side (sec-
ond execute).
Execute heading angle (degrees): heading
at which the rudder is reversed.
Overshoot angle (degrees): the angle
through which the ship continues to turn in the
original direction after the application of coun-
ter rudder. The first and second overshoot an-
gles correspond to the maximum heading angle
reached after the second and third execute,
respectively.
Time to check yaw (tS, tB) (sec): the time
between the rudder execute and the time of the
maximum heading change in the original direc-
tion.
Heading (degrees): the course deviation
fromthe straight initial course.
Reach tA (sec): the time between the first
execute and the instant when the ships headingis zero after the second execute.
Time of a complete cycle T(sec): the time
between the first execute and the instant when
the ships heading is zero after the third exe-
cute.
Angular speed & (deg/sec): constant yaw
rate (time gradient of heading) established after
the second execute. In this phase the ship exe-cutes circular motion, if steady speed is as-
sumed.
Unit time: the time required for the vessel
to travel her own length at approach speed (=
L/V). The time for a complete cycle is ex-
pressed in unit times.
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2.2.3 Modified Zigzag ManoeuvreThe test procedure for a modified zigzag
manoeuvre is the same as for 2.2.2. (zigzag
manoeuvre), but the execute heading angle is
chosen to be as small as 1 degree, the rudder
angle being 5 or 10 degrees.
The modified Z-manoeuvre test is used to
express course-keeping qualities in conditions
similar to actual operations characterised by
small heading changes and rudder values.
2.2.4 Zigzag Manoeuvre at Low SpeedThis manoeuvre is executed while the ship
is running ahead by inertia after stopping themain engine. When the ship's speed drops be-
low 5 knots, a 35/5 zigzag manoeuvre is initi-
ated. The above procedure to be repeated until
the ship's heading does not react to the rudder
actions.
2.2.5 Spiral ManoeuvreSpiral manoeuvres are applied to assess thecourse stability of the ship (see Figure 3). For
ships, which show stable characteristics either
the direct (Dieudonn) or reverse (Bech) spiral
methods can be used to obtain response at low
rudder angles. For unstable ships, the Bech
reverse spiral is recommended within the limits
indicated by the results of the pullout manoeu-
vres.
Direct Spiral Manoeuvre. With the ship on
an initial straight course, the rudder is put to
about 25 degrees to starboard and held until the
rate of change of heading is constant. The rud-
der angle is then decreased by 5 degrees and
again held until steady conditions of yawing
have been obtained. This procedure is repeated
until the rudder has covered the range from 25
degrees on one side to 25 degrees on the otherside and back again. Over the range of rudder
angles of 5 degrees on either side of zero or
neutral rudder angle these intervals should be
reduced.
Figure 3: Presentation of spiral manoeuvre
results
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The achieved steady rate of turn is regis-
tered for each rudder angle.
This manoeuvre should be carried out as in
still air and calm water conditions as possible.
Reverse Spiral Manoeuvre. In the Bech re-verse spiral the ship is steered at a constant rate
of turn and the mean rudder angle required to
produce this yaw rate is measured.
The necessary equipment is a rate-gyro (al-
ternatively the gyro compass course may be
differentiated to provide & ), and an accurate
rudder angle indicator. Experience has shown
that accuracy can be improved if continuous
recording of rate of turn and rudder angle is
available for the analysis.
When several spiral tests are to be made, an
auto-pilot can be used to perform the reverse
spiral.
If manual steering is used, the instantane-
ous rate of turn must be visually displayed for
the helmsman, either on a recorder or on a rate
of turn indicator.
Using the reverse spiral test, points on the
curve rate of turn versus rudder angle may be
taken in any order. However, if the ship is
steered manually, the procedure originally pro-
posed by Bech can be recommended. The ship
is made to approach the desired rate of turn,
& , by applying a moderate rudder angle. Assoon as the desired rate of turn is obtained, the
rudder is actuated such as to maintain this rate
of turn as precisely as possible. The helmsman
should now aim to maintain the desired rate of
turn using progressively decreasing rudder mo-
tions until steady values of speed and rate of
turn have been obtained. Steady rate of turn
will usually be obtained very rapidly, since rate
steering is easier to perform than normal com-
pass steering. However, adjustments to the
rudder angle may be required until the shipachieves a steady speed; therefore, it is neces-
sary to allow some time before the values of
& and are measured.
Figure 4: Presentation of pull-out manoeuvre
results
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2.2.6 Pullout TestThe pullout manoeuvre is a simple test to
give a quick indication of a ship's course stabil-
ity.
A rudder angle of approximately 20 degreesis applied until the ship achieves a steady rate
of turn; at this point, the rudder is returned to
midships. If the ship is stable, the yaw rate will
decay to zero for turns to both port and star-
board. If the ship is unstable, then the rate of
turn will reduce to some residual yaw rate. The
pullout manoeuvres have to be performed to
both port and starboard to show a possible
asymmetry (see Figure 4). Pullout manoeuvres
can be performed at the end of a zigzag or turn-
ing circle test.
2.2.7 Stopping TestDuring stopping tests a ships speed is re-
duced from some initial steady value to zero by
applying full astern power.
The most common stopping trial starts from
full ahead speed. When the approach condi-
tions are satisfied, the demand for full astern
power is given from the engine control position
on the bridge.
When the propelling unit has reached
steady full astern rpm and ships speed be-
comes zero, the test is completed.
The parameters measured during crash-stop
and stopping trial are (see Figure 5):
the head reach which is defined as distancetravelled in the direction of the ship's initial
course;
the track reach which is the total distancetravelled along the ship's path;
the lateral deviation which is the distance to port or starboard measured normal to theship's initial course.
Figure 5. Definitions used in stopping trials
Ships usually are directionally uncontrolla-
ble during this manoeuvre so that the trajectory
is, to a large extent, determined by the ambient
disturbances, initial conditions and rudder ac-
tions. Although existing procedures allow rud-
der activity to keep the ship as close to the ini-
tial course as possible, it should be noticed that
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IMO requires the rudder to be maintained at
midship throughout the trial.
2.2.8 Stopping Inertia TestStopping inertia tests are performed to as-
sess the behaviour of a ship during deceleration
without propeller action.
Starting from full ahead speed, the engine is
stopped quickly. When the ship's ahead speed
has reduced to 5 knots, the test is completed.
The parameters measured during a stopping
inertia test are:
the head reach which is defined as distancetravelled in the direction of the ship's initial
course;
the track reach which is the total distancetravelled along the ship's path;
the lateral deviation which is the distance to port or starboard measured normal to the
ship's initial course;
the duration of the manoeuvre.
2.2.9 Man-overboard TestMan-overboard manoeuvres are performed
to provide information on the time taken and
the deviation from course necessary to retrieve
a person or object from the sea. The elliptical
and Williamson turns are two well-known
man-overboard manoeuvres. These manoeu-
vres will, in the absence of wind and current,
bring the ship back to the position where the
man overboard incident occurred.
The elliptical turning manoeuvre. With the
ship initially under approach speed, the rudder
is moved quickly to hard over starboard and
held until ship has altered course by 180 de-grees from initial course. At that time, the rud-
der is moved quickly to hard over port and the
ship is steadied on the original course. This
manoeuvre is to be terminated when the ship
has returned to the position, or nearest position,
where the manoeuvre was initiated.
The Williamson turning manoeuvre. With
the ship initially under approach speed, the
rudder is moved quickly to hard over starboard
and held until ship has altered course by 70degrees from initial course. At that time, the
rudder is moved quickly to hard over port, until
the ship is heading 180 degrees from initial
course. This manoeuvre is to be terminated
when the ship has returned to the position, or
nearest position, where the manoeuvre was
initiated.
Following data are to be derived from the
trials:
1) a plot of the ships track,2) the time taken to return to the point, or
nearest position to that point, at which the
manoeuvre was initiated
3) the lateral deviation from the initial courseat the point, or nearest position to that
point, at which the manoeuvre was initiated
are to be derived.
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2.2.10 Parallel Course Manoeuvre TestThe parallel course manoeuvre provides in-
formation on the ship's side reach.
With the ship initially under approach
speed, the rudder is moved quickly to hard overstarboard and held until the ship has altered
course by 15 degrees from initial course. At
that time, the rudder is moved quickly to hard
over port. When the ships heading resumes the
initial course, the rudder is moved to midship.
The test has to be repeated for 45 degrees
and 90 degrees change of heading from initial
course.
Following data are to be derived from the
trials:1) a plot of the ships track,2) the time taken to reach parallel course,3) the lateral deviation between the initial and
final positions.
2.2.11 Initial Turning TestThe initial turning trial provides informa-
tion on the effectiveness of the rudder in tran-
sient manoeuvres and to ascertain the ships
initial turning ability.
With the ship initially under approach
speed, the rudder is moved quickly to 10 de-
grees and held until the ship has altered course
by 10 degrees from initial course.
Following data are to be derived from the
trials:
1) a plot of the ships track,2) the track reach, being the total distance
travelled along the ships path, non-
dimensionally expressed in ship lengths.
These data can also be obtained from the
first phase of a 10/10 zigzag manoeuvring trial,between the first and the second execute.
2.2.12 Accelerating Turning TestAccelerating turning test provide the ability
to make a "kicking" turn at slow speed, which
is used in harbour manoeuvres.
The ship is initially at standstill with zero
speed and propeller stopped.
The manoeuvre is started by ordering the
rudder hard over and the engine half ahead on
telegraph. Rudder and engine control are there-
after kept constant during the turn. The turn
continues until a 180 degrees change of head-
ing has been completed.
The essential information to be obtained
from this manoeuvre consists of:
tactical diameter, advance,
transfer, final speed, time to change heading 90 degrees time to change heading 180 degreesThe first three of these may be presented in
non-dimensional form by dividing their values
by ship's length between perpendiculars (LPP).
Maximum advance and maximum transfer can
be measured, too.
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2.2.13 Thruster TestFor a ship fitted with lateral thrusters the
following tests are recommended.
Turning Manoeuvre. With the ship initially
at low speed (between 0 and 8 knots), thethrusters are ordered to deliver full power
while the rudder is kept amidships. The ma-
noeuvre should be continued until 90 degrees
change of heading has been completed. Tests
should be conducted both to port and starboard.
The initial conditions include the ship bow
being oriented directly into the wind.
The essential information to be obtained
from this manoeuvre consists of:
advance, transfer, final speed, time to change heading 90 degrees.The first two of these may be presented in non-
dimensional form by dividing their values by
ship's length between perpendiculars (LPP).
Zigzag Manoeuvre. With the ship initially
at low speed (between 3 and 6 knots), the
thrusters are ordered to deliver full power
while the rudder is kept amidships. The testfollows the same sequence as the zigzag ma-
noeuvre (see 2.2.2) where at the instants of the
executes, the thruster action is reversed instead
of the rudder action. An execute heading angle
of 10 degrees is suggested.
It is recommended for special types of ships
such as ferries to carry out zigzag manoeuvres
as above with a speed of approximately 3 knots
astern.
2.2.14 Crabbing TestA ships ability to move transversely at
zero forward speed without altering heading is
verified with a crabbing test. The purpose of
the test is to document the maximum possible
transverse speed.
All available propellers/rudders/thrusters
should be used to perform the test. Obviously a
conventional ship with only one propeller, one
rudder and no bow thruster cannot perform
crabbing according to this definition.
The essential information to be obtained
from this manoeuvre consists of the final
steady lateral speed of the ship. The forward
speed and the change of heading should also bedocumented, although they should be kept as
low as possible.
The use of propeller(s), rudder(s) and
thruster(s) should be documented, including
power, rpm, pitch, thrust direction, rudder an-
gle, etc.
The test should be carried out in as still air
and calm water conditions as possible. If the
wind is in excess of Beaufort 2 the test should
be carried out in beam wind, crabbing both
with the wind and towards the wind. Wind,
current and sea conditions should be docu-
mented.
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3 PARAMETERS
3.1 Ship Parameters
Following ship related parameters should
be documented:
Ship type and design parameters (L/B, B/T,CB)
Hull conditions at trial condition (L/B, B/T,CB, GM)
Submerged lateral area Lateral/longitudinal projected area above
waterline
Stern type parameters at trial condition Rudder type Number of rudders Rudder area Rudder angle or pod angle Propeller type Propeller diameter and pitch Number of propellers and turning direction
of each propeller
Engine type Power and percentage of Maximum Con-
tinuous Rating to which ship speed and
RPM apply
3.2 Manoeuvring Trial Measurements
3.2.1 Initial ConditionsThe following data is to be clearly recorded
for each trial:
Date Time Area of trial
Initial approach speed and heading Ships loading condition (draft, trim, longi-
tudinal centre of gravity and transverse
metacentric height)
Radii of gyration Heel angle Water depth Environmental conditions, including Current speed and relative direction Wind speed Wind direction relative to the ships
head
Sea state3.2.2 Manoeuvring Data
During the different trials, the data listed in
Tables 2 and 3 have to be measured and re-
corded from the start of the approach run until
the end of the manoeuvring trial.
4 DATA ACQUISITION SYSTEM
4.1 Calibration of Instruments
4.1.1 Ship speed and positionShip speed and position should be deter-
mined using either the measured mile, elec-
tronic tracking or GPS. It is preferable to use
GPS due to its flexibility. As mentioned previ-
ously, trials should be conducted in sheltered
waters, of adequate depth, with minimal cur-
rents and tides. GPS, when used in the differen-
tial mode, allows correction of the data to a
known reference site. Pulse radar track is also
recommended, however, the flexibility is not as
great as with GPS.
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4.1.2 Ships headingA gyrocompass should be used to record
ships heading. The gyro repeaters are to be
adjusted until they are synchronised with the
master gyro compass reading.
4.1.3 Rudder angleRudder angle should be measured by ade-
quate instrumentation (e.g. angular potentiome-
ter) installed on the rudder stock. The steering
gear is to be tested to calibrate the rudder angle
indicator(s), over the full range of movement
against the actual rudder angle reading given
on the rudder stock.
4.1.4 Rate of turnThe rate of turn indicator can be calibrated
against the actual change in heading per second
during a turn.
4.1.5 Shaft rpmPropeller shaft rpm should be determined
by installing either a magnetic probe or infra-
red optical sensing device. Sixty metal strips or
reflective tapes should be installed so that in-
stantaneous rpm can be determined.
4.1.6 TorqueThe torque should be measured using a tor-
sion meter that can be calibrated. The residual
shaft torque (zero of the torsion meter) should
be taken immediately before and after the trials
by rotating the shaft slowly in both directionswith turning gears and the torque values de-
rived from the torsion meter should be adjusted
accordingly. Obtaining torque by attaching
strain gages on the shaft is not recommended
since alignment of the gages is most difficult
and they cannot be physically calibrated once
installed.
4.2 Acquisition Systems
Data should be acquired by a computer-
based system because almost all the manoeu-
vring trials require time history data. The sys-
tem should be able to collect, record and proc-
ess real-time trial data of all measured parame-
ters. Data sampling rate of 0.5 - 2 samples per
second is suggested.
At a minimum, the data acquisition system
should be capable of recording the signal time-
trace relevant to the following quantities:
time ship position and speed ship heading and yaw rate rudder angle shaft torque and rpm roll angle
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Table 2 Recommended Manoeuvring Trial Measurements
Type of test Heading PositionForward
speed
Rudder
angle
rpm Rate of
turnTorque
1 Turning test **2 Z-manoeuvre test 3 Modified Z-manoeuvre 4
Z-manoeuvre at low
speed test
5 Direct spiral test *6 Reverse spiral test *7 Pullout test *8 Stopping test 9 Stopping Inertia test
10 Man-overboard test 11
Parallel course manoeu-
vre test
12 Initial turning test 13 Accelerating turning test 14 Thruster test 15 Crabbing test
*If the rate of turn cannot be obtained using a rate gyro and/or gyrocompass, the differential of the
heading angle has to be used to derive this parameter
** Recommended for trials with twin propeller ships
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Table 3 Data sampling rate and accuracy requirements
Parame-
ter
Turning
test
Pull-out
test
Stopping
test
Zig-zag
manoeuvre
Spiral test Man-
overboard
test
Mini-
mum
accuracy
Time Continuously Continuously Continuously Continuously Continuously Continuously 1 s
Position Initially, andthen 45 degree
change of
heading-
Initially, andthen 20 s
At least 5equally spaced
measurements-
Initially, then45 degree
change of
heading or 20 s
which-ever is
the lesser
10 metres
Forward
Speed
10 s or 30
degree change
of heading-
5 s 5 s Initially, then
once at each
steady rate of
turn
5 s 0.5 knots
Heading 5 s 2 s 20 s 2 s 2 s 2 s 0.5 degrees
Setting of
manoeu-vring de-
vice
(Rudder
angle)
Initially, and
then 45 degree
change ofheading
2 s Initially, and
then periodi-
cally to checkthe rudder is
amidships
2 s 2 s 2 s 1 degree
Propeller
rpm and
torque
Initially, and
then at least
every 45 degree
change of
heading
-
Initially, and
then 5 s
Initially, and
then at least at
every crossing
of the base
course
Initially, and
then once at
each steady turn
Initially, then
when the
rudder is
reversed and at
the end of the
manoeuvre
1% ofinitial setting
Rate of turn 5 s 2 s
-
5 s 5 s
-
0.05 degs/s
Heel angle 5 s 2 s 20 s 2 s 2 s 2 s 0.5 degrees
Propeller
pitch
5 s 2 s
-
5 s 5 s
-
0.05 degs/s
Note
All parameters are to be measured at the initiation and termination of points of each manoeuvring trial
It should be indicated how position and speed have to be measured. A distinction should be made be-
tween forward speed, length of speed vector, speed corrected for current, etc.
(adapted from Lloyds Register Provisional Rules, 1999)
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5 VALIDATION
5.1 Uncertainty Analysis
Trial data uncertainty analysis should be
carried out to assess the level of confidence inthe trial results and to provide the statistics
associated with ship trial measurements.
For the uncertainty analysis of ship position
and speed, shaft rpm and torque, reference can
be made to the uncertainty analysis section of
the ITTC Guide for Speed/Powering Trials (4.9
- 03 - 03 - 01.3).
The effect of errors in rudder angle or ma-
noeuvring device setting on the manoeuvre isdifficult to assess through conventional uncer-
tainty analysis. It is recommended to make use
of simulation techniques for this purpose.
5.1.1 Correction due to EnvironmentThe immediate environment such as wind,
waves and current can significantly affect ship
manoeuvrability. IMO Resolution A.751
(1993) suggests a method to account for envi-
ronmental effects only for turning tests. Recent
research concerning environmental effects on
zigzag tests has shown that no straightforward
correction method can be applied. For such
complicated manoeuvres simulation techniques
are the only possible solution.
5.1.2 Correction due to Ship ConditionsShip manoeuvrability can be significantly
affected by the draft and trim condition. Course
stability in ballast condition is usually better
than in full load even-keel conditions. If this is
not possible, the manoeuvring characteristics infull load even keel condition should be pre-
dicted and corrected using a reliable method
(i.e. model tests or proven computer simula-
tion) that ensures satisfactory extrapolation of
trial results, as also suggested by IMO Resolu-
tion A.751 (1993). In this case, however, the
procedure must be clearly referenced and
documented.
5.2 Benchmark Tests
Preliminary Analysis of ITTC Co-operative
Tests Programme (11th 1966 pp.486-508) A
Mariner Class Vessel
The 11th I.T.T.C. Standard Captive-Model-
Test Program (11th 1966 pp.508-516) A Mari-
ner Type Ship " USS COMPASS ISLAND"
Co-operative Tests for ITTC Mariner Class
Ship Rotating Arm Experiments(12th 1969
pp.667-670)A MARINER Model
The Co-operative Free-Model Manoeuvring
Program (13th 1972 pp. 1000) Co-operative
Test Program - Second Analysis of Results of
Free Model Manoeuvring Tests(13th 1972 pp.
1074-1079) A MARINER-Type Ship
The Co-operative Captive-Model Test Program
(13th 1972 pp.1000) To Determine the Ability
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with which Full-Scale Ship Trajectories Could
Be Predicted from the Test Data Acquired.
Co-operative Tests Program - Review and
Status of Second Phase of Standard Captive-
Model Test Program (13th 1972 pp. 1080-
1092)
The Mariner Model Co-operative Test Program
-Correlations and Applications- (14th 1975
Vol.2 pp. 414-427) A New Large Amplitude
PLANAR-MOTION-MECHANISM. The
MARINER Model
Comparative Results from Different Captive-
Model Test Techniques(14th 1975 Vol.2
pp.428-436)
A MARINER CLASS Vessel and a Tanker
Model
Ship Model Correlation in Manoeuvrabil-
ity(17th 1984 pp.427-435) To Conduct Model
Tests and Compare Their Results with "ESSO
OSAKA' Deep and Shallow Water Trials Joint
International Manoeuvring Program (JIMP) A
Working Group Called JAMP (Japan Manoeu-
vrability Prediction)
Free-Running Model Tests with ESSO
OSAKA(18th 1987 p.369-371)
Captive Model Tests with ESSO OSAKA(18th
1987 pp.371-376)
Manoeuvring Trial Code(14th 1975 pp.350-
365)
ITTC Quality Manual(22nd ITTC QS Group
4.9-03/04-01)
Guide for Planning, Carrying out and Report-
ing Sea Trials(ISO/TC8/SC9, 1999-10-19)
Interim Standards for Ship Manoeuvrabil-
ity(IMO Resolution A.751(18), 1993)
Classification of the Manoeuvring Capability
of Ships(Lloyds Register Provisional Rules,
May 1999)
Excerpts regarding the Conduct of
Speed/Power Trials, Uncertainty Analysis and
Correction of Trials Data(22nd ITTC TRIALS
& MONITORING SPECIALIST COMMIT-
TEE